Temperature sensing device for detecting an acceleration or shock provided with a heating unit, and associated method

ABSTRACT

A sensor is used for measuring the motion of a fluid in relation to a heating device. A temperature-measuring means is provided in such a way that the temperature of the fluid is measured at a measuring location as a function of the motion of the fluid, as a measuring location, the location of the heating device or its immediate vicinity being provided.

FIELD OF THE INVENTION

The present invention is directed to a sensor having a heating device.

BACKGROUND INFORMATION

To detect an impact, e.g., when an object strikes a motor vehicle, it isconventional to use acceleration sensors mounted in the motor vehicle.For the most part, these sensors evaluate the motion of a seismic mass.Also conventional, however, are sensors based on thermal operatingprinciples. For example, such a known sensor has a trench that isspanned in the transverse direction by freely suspended bridges. One ofthese bridges is used as a heating element, while two adjacent bridgesfunction as temperature sensors. The heating produces a temperaturegradient, going out from the heating element in the direction of thetemperature sensors. A sudden acceleration of the sensor changes thetemperature gradient. Such known thermal acceleration sensors arerelatively rugged, since, in contrast to sensors having a seismic mass,they do not include any movable parts. However, this rugged quality islimited by the fine, freely suspended bridges. They are especiallyvulnerable to particles present in the ambient environment of the freelysuspended bridges, thus, for example, in the air. Moreover, they areexpensive to manufacture, since, for example, conventional sawingprocess are impossible or difficult to use for these sensors.

SUMMARY

A sensor according to an example embodiment of the present invention andthe method according to the present invention may have the advantagethat a simpler, more rugged sensor and an evaluation method or ameasurement method are provided. In addition, it may be advantageousthat the heating device and the temperature measuring means are providedat one and the same location, i.e., in the immediate vicinity of oneanother. This enhances the stability and, respectively, the ruggednessof the sensor system.

In contrast to conventional sensors, in the design according to thepresent invention of a thermal impact and acceleration sensor, there isno dependence of the output signal on the inclination of the sensor.Moreover, the output signal is independent of the direction in which theacceleration takes place.

It is furthermore advantageous if the electrical resistance of theheating device and a wiring of the heating device are provided astemperature-measuring means. Thus, in accordance with the presentinvention, it is possible for the heating device to implement both thefunction of heating, as well as that of temperature measurement. Thismakes the sensor system of the present invention simpler and lessexpensive to manufacture, so that it may be provided as a more ruggedsensor at an equivalent price.

It is also advantageous if the heating device is provided for operationat a constant current, a constant voltage, or a constant power, thecurrent, the voltage or the power being provided, in particular, as afunction of a signal of an ambient-temperature sensor. The sensor systemof the present invention is, therefore, able to be designed tocompensate for measuring sensitivity over a broad ambient temperaturerange.

It may also be advantageous if a thermocouple is provided at thelocation of the heating device or in its immediate vicinity. In thisway, it is possible to provide a measurement of the temperature of thefluid that is independent of the electrical resistance of the heatingdevice.

Furthermore, it may be advantageous if a plurality of heating devicesand a plurality of temperature-measuring means are provided. In thisway, on the basis of the comparison of the time characteristic of thetemperatures measured using the temperature-measuring means, it ispossible to deduce the direction of impact. In one arrangement of aplurality of heating devices and their wiring configuration in the formof a Wheatstone bridge, one variant of the sensor system of the presentinvention is also able to provide an augmented output signal. Inaddition, when working with a plurality of heating devices, on the basisof the temporal location of the signals and the amplitudes, it ispossible to measure the direction and the intensity of impact.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention are illustrated in thedrawings and are explained in greater detail in the followingdescription.

FIG. 1 shows a conventional system.

FIG. 2 shows a first example embodiment of the sensor system accordingto the present invention in a perspective and in a sectional view.

FIG. 3 shows a sensor system according to the present invention,including a first variant of the heating device.

FIG. 4 shows a the sensor system according to the present invention,including a second variant of the heating device.

FIG. 5 shows a second example embodiment of the sensor system accordingto the present invention, in a plan view.

FIG. 6 shows a third example embodiment of the sensor system accordingto the present invention, in a plan view.

FIG. 7 shows a block diagram of an evaluation electronics for the firstexample embodiment of the sensor system according to the presentinvention.

FIG. 8 shows one possible implementation of a part of the evaluationcircuit.

FIG. 9 shows a block diagram of an evaluation electronics for the secondexample embodiment of the sensor system according to the presentinvention.

FIG. 10 shows a block diagram of an evaluation electronics for the thirdexample embodiment of the sensor system according to the presentinvention.

FIG. 11 shows a representation as a function of the time of the usefulsignal of a sensor system according to the present invention, given alighter impact.

FIG. 12 shows a representation as a function of the time of the usefulsignal of a sensor system according to the present invention, given aheavier impact.

FIG. 13 shows another design variant of the sensor system according tothe present invention.

FIG. 14 shows a fourth specific embodiment of the sensor systemaccording to the present invention.

FIG. 15 shows a fifth example embodiment of the sensor system accordingto the present invention.

FIG. 16 shows four representations as a function of the time of theuseful signals in accordance with the fourth example embodiment of thesensor system according to the present invention.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 shows illustratively a conventional sensor for detecting animpact, e.g., when an object strikes a motor vehicle, in accordance withthe related art. The conventional sensor is provided with referencenumeral 100. Sensor 100 includes a trench 120 which is spanned in thetransverse direction by extremely fine, freely suspended bridges. Theseare denoted in FIG. 1 by reference numerals 130 and 140. One of thesebridges is used as a heating element 130, while adjacent bridges 140function as temperature sensors. As a result of the heating, atemperature gradient forms, starting from heating element 130, in thedirection of the temperature sensors. A sudden acceleration of thesensor, for example due to an impact, effects a change in thetemperature gradient. This change is detected via temperature sensors140 and is converted by an evaluation electronics into an output signalproportional to the acceleration. The disadvantage of this system isthat the fine, freely suspended bridges 130, 140 are not very rugged.These bridges are susceptible to particles found in the air or in themedium surrounding the bridges. Moreover, they are expensive tomanufacture, since, for example, it is not possible to use aconventional sawing process when working with these sensors.

FIG. 2 shows a sensor 1 or a sensor system 1 according to an exampleembodiment of the present invention, in a perspective view in the toppart of the figure and in a sectional view in the bottom part of thefigure. Sensor 1 is implemented in a substrate 10 which is provided, inparticular, as semiconductor substrate 10. For example, substrate 10 isalso referred to in the following as silicon substrate 10. However,another semiconductor material may also be used as a substrate, or amaterial which is not a semiconductor may also be used as a substrate.Provided in substrate 10 of sensor 1 is a cavity formation 20 which isvisible in FIG. 2, in the sectional view in the bottom part of thefigure. Cavity 20 is able to be produced, for example, from the rearside of substrate 10 using bulk micromechanical technology. After cavity20 is produced in substrate 10, a diaphragm 25 remains on the front sideof substrate 10. Cavity 20 is formed in accordance with the exampleembodiment of the present invention, in particular, by etching of cavity20 into silicon substrate 10. Cavity 20 is sealed off on the front sideof substrate 10 by diaphragm 25 which has dielectric properties and isthermally insulating. At least one temperature-dependent resistor 30,for example of platinum, is situated on diaphragm 25. Other exampleembodiments of sensor system 1 of the present invention also provide, inaddition to temperature-dependent resistor 30, other resistors or athermocouple on diaphragm 25. In the example embodiments of the presentinvention, diaphragm 25, together with the structures situated thereon,has a small thermal mass and, thus, a low thermal time constant. Thus,it is possible to provide sensor systems 1 which have a time constant inthe range of 5 milliseconds up to 15 milliseconds. In operation,resistor 30 or, given a plurality of resistors, at least one of theseresistors is electrically heated. If sensor 1 is at rest, i.e., if noacceleration forces act on the sensor, then a narrowly limited volume ofheated gas, such as air, or a convection current of the gas forms aboveand below electrically heated resistor 30. The temperature of resistor30 and thus its resistance value adjusts to a constant value. If thesensor is accelerated and, in the process, undergoes a large enoughdeflection path amplitude, for example due to a jerky or impact-typelateral motion, then the inertia of the cold air in the ambientenvironment of the heated air volume, i.e., generally of the fluidvolume, causes the heated volume to move away from the sensor, i.e., inthis case, away from the location of the temperature measurement. Due tothe low time constant of diaphragm 25, resistor 30 cools offaccordingly. This leads to a change in the resistance value of resistor30 which may be detected using an evaluation device or an evaluationelectronics. The evaluation electronics includes means for heatingresistor 30 and means for measuring the resistance value of resistor 30and for converting the same into an electrical useful signal. Sensor 1and the evaluation electronics may be used for detecting suddenlyoccurring impacts. The signal amplitude of the useful signal isdependent on the intensity of the impact. For that reason, sensor 1 mayalso be used for an acceleration measurement. In accordance with thepresent invention, it is useful when the deflection amplitude of theimpact is great enough, for example, a few millimeters, to enableresistor 30 to move away from under the heated gas volume and, thus,“see” a different temperature. It is also clear, however, that theminimum amplitude of the impact with regard to the deflection pathbecomes all the smaller, the smaller the dimensions of resistor 30 or ofcavity 20 and of the entire sensor system 1 are.

Sensor system 1 according to the present invention has a rugged designand may be manufactured using standard processes. Since there is no needfor seismic masses, which could strike against a stop means in responseto a heavy impact, such a sensor according to the present invention maybe used to measure large impact-intensity ranges without potentiallydamaging sensitive movable parts in sensor 1.

In this context, sensor 1 is based on the principle that resistor 30 isprovided as heating device 30. Heating device 30 is in thermal contactwith a fluid, in particular a gas, which is contained in cavity 20 or isalso situated on the top side of diaphragm 25. Without the influence ofan accelerating force acting on sensor 1, the heating action of heatingdevice 30 results in a thermal equilibrium in the form of a constantheat flow from heating device 30 into the fluid. If sensor system 1,together with its heating device 30, is subjected to an acceleratingforce, then the inertia of the fluid results in a motion of the fluidrelative to heating device 30, thereby changing the thermal equilibrium,which leads to a temperature change at the location of the heatingdevice or in its immediate vicinity. In accordance with the presentinvention, at the location of heating device 30 or in its immediatevicinity, a temperature-measuring means is provided, which is able todetect the change in the thermal equilibrium on the basis of atemperature change. As a result, the motion of the fluid in relation toheating device 30 is measurable. In a first and second exampleembodiment of sensor 1, the present invention provides for theelectrical resistance value of heating device 30 to be used as atemperature-measuring means. A third example embodiment of sensor 1provides for a temperature-measuring means that is separate from heatingdevice 30.

In accordance with various example embodiments of the present invention,thermally insulating diaphragm 25, in particular of silicon oxide andsilicon nitride, is provided over cavity 20. The formation of diaphragm25 in the silicon oxide and silicon nitride is especially useful inaccordance with the present invention when silicon is used as substrate10. A heating device 30 or a plurality of heating devices 30, which maybe differently formed, are located on diaphragm 25. A first variant ofthe form of heating device 30 in a meander shape is shown in FIG. 3, anda second variant of the form of heating device 30 in a helical shape isshown in FIG. 4. Both in FIG. 2 as well as in FIGS. 3 and 4, resistor 30or heating device 30 is electrically connectible to connection surfacesand bonding pads (reference numeral 36) and to leads 35. Bonding pads 36and leads 35 are provided on substrate 10. Resistor 30 is provided, inparticular, of platinum.

FIG. 5 shows a second example embodiment of sensor 1 according to thepresent invention. Besides heating device 30 in the region of diaphragm25, in the second example embodiment, an ambient-temperature sensor 50is provided on substrate 10 and is likewise connectible via bonding padsand leads, which, however, are not denoted by reference numerals. Inaccordance with the present invention, ambient-temperature sensor 50 islikewise provided of platinum, in particular. Ambient-temperature sensor50 is provided for detecting the ambient temperature. The resistancevalue of the ambient-temperature sensor may be used to compensate forthe measuring sensitivity of the temperature-measuring means accordingto the present invention over a broad ambient-temperature range.

FIG. 6 shows a third example embodiment of sensor system 1 according tothe present invention. In contrast to the first example embodiment, athermocouple 31 that is separate from heating device 30 is provided. Itmeasures the temperature of the fluid at the location of the heatingdevice or in its immediate vicinity. Thermocouple 31 is designed as atemperature sensor and is linked via special leads 311 on substrate 10to bonding pads which are not denoted by reference numerals. Inaccordance with the present invention, the third example embodimentprovides for thermocouple 31 directly at the location of heating device30 or in its immediate vicinity. In this connection—for the case of ameander shape of heating device 30 on diaphragm 25—the location ofheating device 30 is understood to be the entire diaphragm surface whichis more or less covered by the meander structure of heating device 30.Even when thermocouple 31 is provided next to a resistance line ofheating element 30, but within a loop of the meander-shaped structure ofheating device 30, it is nevertheless positioned at the location ofheating device 30, since even when heating device 30 is used astemperature-measuring means, no better spatial resolution would bepossible with respect to temperature detection.

At its tip, thermocouple 31 includes a hot connection (letter A in FIG.6) and, at its connection to leads 311 (letter B in FIG. 6), a coldconnection. In a third embodiment of sensor system 1 of the presentinvention, it is also possible, of course, to provide a plurality ofthermocouples 31 at the location of heating device 30 or in itsimmediate vicinity.

A block diagram of the evaluation electronics for the first embodimentof sensor 1 according to the present invention is illustrated in FIG. 7.It is provided in accordance with the present invention that the heatingresistor provided as heating device 30 is operated on diaphragm 25 usinga constant current or a constant voltage or a constant power. This isillustrated in FIG. 7 for the case of a constant current. The heatingcurrent is denoted in FIG. 7 by reference numeral 300. The resistancevalue of heating device 30 is denoted in FIG. 7 by reference numeral310. To generate constant heating current 300, a constant current source301 is provided in accordance with the present invention. Heatingresistance 310 is measured using the voltage drop across it as a basis,and fed to an amplifier circuit 60. Following amplification in amplifiercircuit 60, an offset correction is made in an offset-correction device65 using an offset-correction voltage 650, and the signal issubsequently filtered in a filter device 70. From filter device 70,useful signal 700 is then able to be picked up in comparison to ground698.

One possible implementation of the evaluation circuit of FIG. 7 is shownin FIG. 8, filter device 70 having been omitted, however. A firstoperational amplifier 330, which is connected to supply voltage 699 andground potential 698, is used for adjusting constant heating current 300through heating resistor 310, which is switched between the output offirst operational amplifier 330 and its inverting input. Thenon-inverting input of the first operational amplifier is connected tothe tapping point of a first controllable resistor 320, which is usedfor adjusting heating current 300. In addition, a first resistor 305 isarranged between mass 698 and the inverting input of first operationalamplifier 330. Output signal 315 of first operational amplifier 330 isamplified by a second operational amplifier 651 and offset-compensated.For this, the output of first operational amplifier 330 is linked via asecond resistor 306 to the inverting input of second operationalamplifier 651. The output of second operational amplifier 651 isadditionally linked via a third resistor 658 to the inverting input ofsecond operational amplifier 651. Thus, second operational amplifier 651is used as amplifier 60. In addition, a second controllable resistor 655is connected between supply voltage 699 and ground potential 698, thetapping point of second controllable resistor 655 being connected via afourth resistor 656 to the non-inverting input of second operationalamplifier 651. Furthermore, the non-inverting input of secondoperational amplifier 651 is linked via a fifth resistor 657 to groundpotential 698. An offset compensation is implemented by the describedsystem at the non-inverting input of second operational amplifier 651.Thus, second operational amplifier 651 also corresponds partially tooffset compensation device 65 from FIG. 7. At the output of secondoperational amplifier 651, (unfiltered) useful signal 700 is adapted tobe tapped off.

FIGS. 11 and 12 show representations of the time characteristic ofuseful signal 700 at the output of an evaluation circuit in accordancewith FIG. 8 for the case that an impact is exerted on sensor system 1 inthe middle of the time characteristic shown. The signal illustrated inFIG. 11 indicates a lighter impact, and the signal illustrated in FIG.12 indicates a heavier impact.

A block diagram of the evaluation electronics for the second exampleembodiment of sensor system 1 according to the present invention isillustrated in FIG. 9. The evaluation electronics for the secondembodiment of the sensor system of the present invention also includesan amplifier device 60, an offset-compensation device 65, in FIG. 9,however, offset-compensation voltage 650 not being shown for the sake ofsimplicity, as well as a filter device 70, at whose output, usefulsignal 700 is present in comparison to ground 698. In contrast to thefirst embodiment, it is provided, however, in the second exampleembodiment of sensor system 1 of the present invention for heatingcurrent 300 to be regulated by heating device 30 as a function of theambient temperature. For this, the second example embodiment providesfor an ambient-temperature sensor 50, which is linked in FIG. 9 to ameasuring transducer 55, which converts the signal ofambient-temperature sensor 50 into a control signal 320 used foradapting heating current 300 to the particular ambient temperature. Tothis end, control signal 320 is fed to a heating-current regulator 32which regulates heating current 300 flowing through heating device 30 asa function of control signal 320. In the process, control signal 320acts, in particular, on controllable constant current source 301.Control signal 320 is a signal generated by the measuring transducer andthe ambient-temperature sensor which adapts the heating of the sensorelement in such a way that the impact sensitivity remains constantwithin a broad ambient-temperature range. It is worth noting in thesecond example embodiment of sensor system 1 of the present inventionthat heating current 300 is still constant with regard to the timescales relevant to the detection of the state of motion of sensor system1, even when it is regulated as a function of the ambient temperature.It is, namely, the case that the time constants for varying the ambienttemperature and, thus, also the time constants for adjusting or changingheating current 300 are much longer or greater than the time constantsfor detecting a motion of the fluid in relation to heating element 30according to the present invention. For that reason, heating current 300may also be regarded as constant in the second example embodiment of thepresent invention with regard to measuring the motion of the fluid.

An evaluation electronics for use with the third example embodiment ofthe sensor system according to the present invention is illustrated inFIG. 10. Heating current 300 flows, in turn, through heating device 30,and resistance value 310 of heating device 30 is dependent on thetemperature of the fluid. Because of the indirect coupling betweenheating device 30 and the temperature-measuring means in the form of athermocouple 31, the third example embodiment of the sensor system ofthe present invention provides that, as an input of the evaluationelectronics, temperature signal 315 is used, which is amplified in anamplifier device 60, is corrected with respect to offset in anoffset-compensation device 65 by an offset compensation voltage 650, andis filtered in a filter device 70 in order to generate useful signal700. In the third example embodiment of the sensor system of the presentinvention, the evaluation electronics is also provided in such a waythat heating device 30 is operated with a constant heating current 300,i.e., alternatively with a constant voltage or a constant power.Thermocouple 31 always supplies a temperature-dependent voltage 315 astemperature signal 315. For output signal or useful signal 700 to begenerated, temperature-dependent voltage 315 is amplified,offset-corrected, and filtered.

FIG. 13 shows another design variant of sensor system 1 according to thepresent invention in a perspective view. Here, a cavity 20 is providedin a substrate 10, a heating device 30 being in thermal contact with thefluid contained, in particular, in cavity 20. In another design variantof sensor system 1 of the present invention, a diaphragm between heatingdevice 30 and the cavity is not provided. Sensor 1 may thus be made upof a substrate 10 or silicon substrate 10, into which cavity 20 isetched in such a way that, freely suspended over cavity 20, atemperature-resistant resistor remains as a heating device 30 in ameander or helical shape. In this way, the thermal mass of resistor 30is reduced as compared to the first, second, and third exampleembodiments of the sensor system of the invention, which include adiaphragm 25. The omission of the diaphragm leads to a low thermal timeconstant and, thus, to a greater sensitivity of sensor 1. FIG. 13, as inthe preceding figures as well, shows a bonding pad 36 and a lead 35 forheating device 35.

FIG. 14 is a fourth example embodiment of sensor system 1 according tothe present invention, a substrate 10 and a diaphragm 25 being provided,in turn, a plurality of heating devices 30, 29, 28, 27 being provided ondiaphragm 25 in the fourth embodiment of sensor system 1 of the presentinvention. Each of heating devices 27 through 30 has two bonding padsand corresponding leads for their electrical connection. For firstheating device 30, this is shown exemplarily by bonding pad 36 and byconnection line 35 in FIG. 14. In the fourth example embodiment of thesensor system of the present invention, it is possible, by comparing thetime characteristic of the resistance values of heating devices 27through 30, to infer the impact direction. For this, it is necessarythat each of heating devices 27 through 30 be connected to an evaluationelectronics in accordance with the first or second specific embodiment.Then, on the basis of the temporal location of the signals of variousheating devices 27 through 30 and their amplitudes, the impact directionand the impact intensity may be measured.

By way of example, FIG. 16 shows four representations of the timecharacteristic of the useful signals of the evaluation electronicsassigned to heating devices 27 through 30, but not shown. In thisconnection, in the first representation, useful signal 700 of heatingdevice 30 is shown. In the second representation in FIG. 16, usefulsignal 729 of the first further heating device 29 is shown. In the thirdrepresentation, useful signal 728 of the second further heating device28 is shown. In the fourth representation, useful signal 727 of thethird further heating device 27 is shown. The signals illustrated inFIG. 16 correspond, in principle, to the signals illustrated in FIGS. 11and 12, a change in operational sign having been made, however. In thissequence, signals 700, 729, 728, 727 have a certain time interval. Inaddition, signals 700 and 729 have a greater amplitude than signals 728and 727. From the temporal position of signals 700, 729, 728, and 727with respect to one another and the pulse level or the signal amplitude,inferences may be made with regard to the impact direction and impactintensity.

FIG. 15 shows a fifth example embodiment of sensor design 1 according tothe present invention. Heating device 30 and first further heatingdevice 29 are provided on diaphragm 25. They are electricallyconnectible via lines and bonding pads, as is explicitly shown in FIG.15 for the example of heating device 30 and the corresponding connectionline 35 or the corresponding bonding pads 36. Heating device 30 andfirst further heating device 29 constitute two thermally very narrowlycoupled heating resistors, which are quasi always at the sametemperature. If they are positioned in opposite branches of a Wheatstonebridge, then an increased measuring signal is able to be generated whichmay be amplified by an amplifier.

FIG. 17 shows an evaluation electronics for a fifth example embodimentof the sensor system according to the present invention. The resistancevalue of heating device 30 is denoted by reference numeral 310, and theresistance value of first further heating device 29 with referencenumeral 290. Together with a seventh resistor 294 and a thirdcontrollable resistor 295, the two resistance values 310, 290 of heatingdevices 30, 29 form a Wheatstone bridge, the tapping point situatedbetween third controllable resistor 295 and resistance value 310 beingfed to the inverting input of a third operational amplifier 602, and thetapping point situated between resistance value 290 of first furtherheating device 29 and seventh resistor 294 being fed to the Wheatstonebridge at the non-inverting input of third operational amplifier 602.Third operational amplifier 602 in FIG. 17 is used comparably toamplifier 60 from the evaluation electronics for the first and secondexample embodiments of the present invention, as depicted in FIGS. 9 and7. In place of filter 70 illustrated in FIGS. 7 and 9 in the evaluationelectronics for the first and second example embodiments of the presentinvention, in FIG. 17, reference numeral 71 denotes a low-pass filter,which is used to limit the band of useful signal 700, which is usefulfor reducing the noise component and increasing the signal-to-noiseratio. Alternatively to the use of a low-pass 71, as filter 70 in FIG.17, a band-pass filter may also be used for filtering 70, thereby makingit possible to eliminate offset voltages and slow drifts of the signal,e.g., due to temperature changes. Through the use of resistance values310, 290 of heating devices 30, 29 in opposite branches of a Wheatstonebridge, an increased measuring signal is able to be generated, which isamplified by an amplifier 60. Using third variable resistor 295, theWheatstone bridge may be balanced.

When using a sensor system having a plurality of heating devices 30, 29,28, 27 on diaphragm 25, it is possible in accordance with the presentinvention to use one of these heating devices 27 through 30 forgenerating a selected temperature jump, in that this resistor isenergized in pulse-like fashion. Thus, a temperature pulse is able to begenerated, which may be measured using other heating devices provided astemperature-measuring means, which are situated on diaphragm 25. Thus, aself-test of sensor 1 may be carried out. The distinction between theself-test pulse and an acceleration may be made on the basis of thedirection of the change in resistance. In the case of an acceleration,the resistor cools for a brief period of time, while, during a selftest, a heating of short duration occurs.

It holds for all example embodiments of the present invention that thesensitivity of sensor 1 may be influenced by the use of filler gasesother than air as fluid, or by the use of different filler pressures ofthe gas surrounding the sensor. Significant in this context is both thedensity of the gas used as well as its thermal capacity. The sensor maythus be adjusted for different measuring ranges.

1-7. (canceled).
 8. A sensor for measuring motion of a fluid,comprising: a heating device; and a temperature-measuring arrangementconfigured to measure a temperature of a fluid as a function of a motionof the fluid at a measuring location, the measuring location being oneof a location of the heating device, or an immediate vicinity of theheating device.
 9. The sensor as recited in claim 8, wherein anelectrical resistance of the heating device and a wiring of the heatingdevice are provided as the temperature-measuring arrangement.
 10. Thesensor as recited in claim 9, wherein the wiring of the heating deviceis provided in such a way that the heating device is provided foroperation at one of a constant current, a constant voltage, or aconstant power.
 11. The sensor as recited in claim 10, furthercomprising: an ambient-temperature sensor, the wiring of the heatingdevice being provided in such a way that, for operation, the heatingdevice is provided one of: i) with a constant current with respect tomeasuring the motion of the fluid, ii) with a constant voltage withrespect to measurement of the motion of the fluid, or iii) with aconstant power with respect to the measurement of the motion of thefluid, the constant current, the constant voltage, or the constant powerbeing provided as a function of a signal of the ambient-temperaturesensor.
 12. The sensor as recited in claim 8, wherein a thermocouple isprovided as a temperature-measuring arrangement, the thermocouple beingprovided at one of the location of heating device, or immediate vicinityof the heating device.
 13. The sensor as recited in claim 8, wherein theheating device includes a plurality of heating devices and thetemperature measuring arrangement includes a plurality oftemperature-measuring arrangements, and wherein for each of theplurality of temperature-measuring arrangements, an electricalresistance of one of the plurality of heating devices and a wiring isprovided.
 14. A method for measuring a motion of a fluid in relation toa heating device, comprising: producing a temperature gradient in thefluid; measuring, at a measuring location, the temperature of the fluidas a function of a motion of the fluid at the measuring location, usinga temperature measuring arrangement; wherein as thetemperature-measuring arrangement, an electrical resistance of theheating device or a thermocouple is used, and wherein the measuringlocation is at a location of the heating device or an immediate vicinityof the heating device.